关键词: 盆栽试验, 分离筛选, 极端耐盐碱菌株, 小麦

Abstract: To provide technical support for the promotion and cultivation of Physocarpus plants, the double setting pot method was used to examine the effects of flooding stress on the photosynthetic characteristics of leaves, including photosynthetic gas exchange and chlorophyll fluorescence, in native species P. amurensisand introduced species P. opulifolius. The net photosynthetic rates (P_n) of leaves of both species were significantly reduced after 15 days of flooding stress, along with decreased stomatal conductance (G_s) and transpiration rates (T_r). Our findings indicated that the decreased photosynthetic capacity of leaves of both species caused by flooding stress was related to the restriction of stomatal factors. Under flooding stress, the photosynthetic inhibition of P. opulifolius was mainly caused by stomatal changes, while that of native P. amurensis was caused by both stomatal and non-stomatal factors. The activity of the PSII reaction center of P. opulifoliusleaves was not significantly affected by flooding stress, which was mainly related to the increase of nonphotochemical quenching (NPQ) that reduced the excess light energy (1-q_P)/NPQ. In contrast, the photochemical activity of the PSII reaction center of native species P. amurensis was significantly reduced by flooding stress. Flooding stress signifi cantly increased the activity of the oxygen-evolving complex (OEC) of the PSII donor side in P. opulifoliusleaves and had little effects on the electron transfer of its acceptor side. Flooding stress significantly inhibited the electronic transfer ability ofQ_A toQ_B in the PSII acceptor side of P. amurensis, but the effect of flooding stress on the activity of OEC in the PSII donor side of P. amurensis was not found. After 15 days of flooding, the relative variable fluorescence (V_L) at the L point was significantly higher than that of P. opulifolius in the standardized O-K curve of P. amurensisleaves, indicating that the degree of thylakoid membrane degradation of P. amurensis leavesunderflooding stress was significantly higher than that of P. opulifolius.P. opulifolius was more resistant to flooding stress than P. amurensis, thus P. opulifolius should be promoted and cultivated in areas with lowlying water.

Key words: isolation and screening, pot experiment, extreme salt-alkali tolerant bacterial strain, wheat.